The kairomonal responses of Thanasimus undatulus (Say), Enoclerus sphegeus F., and Temnochila chlorodia (Mannerheim) to semiochemicals used by Dendroctonus pseudotsugae Hopkins, D. rufipennis Kirby, D. brevicomis LeConte, D. ponderosae Hopkins, and Ips pini (Say) to locate hosts were quantified in the field during the period of D. pseudotsugae dispersal in the spring and early summer. Traps baited with frontalin plus seudenol caught significantly more T. undatulus than traps baited with any other lure. Only a few E. sphegeus were collected during the study, suggesting that it might use semiochemicals other than those tested in this study to locate its prey. All of the traps baited with lures containing exo-brevicomin caught significantly more T. chlorodia than traps baited with other lures. These results suggest that T. undatulus uses seudenol primarily to locate its prey habitat, and T. chlorodia uses exo-brevicomin for the same purpose. These predators likely feed upon bark beetles that produce these compounds or other bark beetles that are found in the same habitats. A secondary pest of ponderosa pine, Pityogenes carinulatus (LeConte), was attracted in significant numbers to the traps baited with I. pini pheromone components. Traps baited with ipsdienol and lanierone caught significantly more P. carinulatus than traps baited with ipsdienol alone.

Pheromone trap catches of the Nantucket pine tip moth, Rhyacionia frustrana (Comstock), are often much higher during the first generation as compared with later generations, regardless of population density or damage levels. One hypothesis proposed to explain this phenomenon is reduced adult longevity during summer due to high temperatures. In this study, adult male and female moths placed in containers in the field during each generation showed significantly shorter life spans during the summer months compared with spring. Life spans were inversely related to the average number of daily degree-days accumulated during the investigations. In the laboratory, adult male moths under varying temperatures and constant humidity showed life spans similar to those observed in the field. Adult male moths that were provided with a sugar water solution in the laboratory did not have significantly longer life spans than those without. Male and female pupal weights showed little variation between generations and sites, and no observable changes in pupal weights occurred during the overwintering period. Some differences in female pupal weight between generations were found at some sites but these differences were not correlated with differences in adult life span. Temperature appeared to be the predominant factor affecting adult moth life span between generations, although other environmental and physiological factors may be important. An understanding of the lower trap catches for R. frustrana during summer may have important implications for using pheromone traps to predict population levels.

The quantity and ratio of two sex pheromone components in the abdominal gland of Rhyacionia frustrana (Comstock) were determined for three generations from the Georgia Piedmont, two generations from the Georgia Coastal Plain, and one generation from the Virginia Coastal Plain. There were no significant differences among quantities of either pheromone component among any generations or collection sites. Quantities for the major component, (E)-9-dodecen-1-yl acetate, varied among the samples from 10.8 to 18.6 ng per adult female. Similarly, quantities for the minor component, (E)-9,11-dodecadien-1-yl acetate, varied from 0.5 to 0.9 ng per female. Ratios were significantly different only between the second generation Georgia Coastal Plain and first-generation Virginia Coastal Plain, although we do not think these differences are biologically meaningful. Pheromone component ratios for the major and minor component ranged from 16.5:1–23.4:1 among all sites. The significance of these findings as they relate to synthetic bait efficacy and decreased summer trap catches of male R. frustrana is discussed.

Larval coccinellids are thought to exhibit random search behavior but recent work has suggested that closer analysis of search paths could reveal more olfaction-driven behavior than previously realized. To test this idea, the use of volatile chemical cues by larvae of the coccinellid Hippodamia convergens Guérin-Méneville in searching for prey tobacco aphids, Myzus nicotianae Blackman, were studied. Larvae (second, third, and fourth instars) were exposed to three volatile sources; aphids alone, aphids on tobacco leaves and tobacco leaves previously exposed to aphids. Larvae were placed in an arena and their search path traced onto a grid then divided into seven different components relating approach angles and velocities at various time intervals. In general, older larvae were more efficient at searching than were younger ones. Older larvae had lower approach angles and higher approach velocities associated with treatments than did younger larvae. Different search behavior components responded differently to the various treatments but in most cases significant effects attributable to olfactory cues were obtained. The results support the potential use of olfactory cues by these larvae and suggest that a more extensive set of analyses and treatments should be conducted.

A 3-yr study was conducted in Louisiana sugarcane field plots to determine the potential of vegetation management and winter cover crops to enhance abundance of the fire ant, Solenopsis invicta Buren, other arthropods, gastropods, and spring sugarcane density. Treatments included pea, clover, and vetch cultivars, a weed-free herbicide treatment, a vetch with herbicide on the row tops; and a mixed weeds treatment arranged in a randomized complete block design. Compared with similar studies conducted during the summer months, spring collections of arthropods in pitfall traps were very low and few differences in arthropod densities occurred. Neither cover crop cultivar nor biomass substantially influenced arthropod density or cane stand density. Slugs (Limacidae) and earwigs (Dermaptera) were most abundant in mixed weed plots. The highest numbers of carabids in 1994 were found in vetch plots, which tended to have higher biomass than other treatments. Soybean oil-soaked bait cards attracted more ants in clover plots than in the plots with vetch plus herbicide. Compared with previous summer studies, we feel that harsher winter weather and other density independent mortality factors during this study period superseded effects of cover crops, vegetation management and quantity of biomass on arthropod densities during the winter. Although positive impacts of winter cover crops were not detected for the variables measured during the study period these data should not be used to suggest that cover crops do not provide agronomic benefit to farmers.

A survey of predatory arthropods in lime orchards at Homestead, FL, showed that spiders significantly outnumbered the other predatory arthropods (the green lacewing Chrysoperla rufilabris, coccinellid Harmonia sp., and the ant Myrmelachista sp.). The spider community consisted of nine families, 25 genera, and 15 species. The abundance and diversity of the predatory spiders in lime orchards suggests their possible role in regulating the increase of arthropod pest populations. In general, comparison of three sampling methods revealed that the visual sampling method provided the highest number of spiders collected followed by the shake-cloth method and the DVAC suction method collected the least. However, our data showed that the choice of sampling method depends on the species of interest. For instance, spider species in the hunting group were collected frequently using the visual method followed by the shake-cloth method; whereas, most of the species in the web-building group were collected by the three sampling methods with similar frequencies. The difference in the efficiency of the sampling methods may be explained by the retreating habits of the different spider species. The data gathered in sampling the predatory arthropods in sprayed and nonsprayed lime orchards demonstrated the probable nontarget effect of the different pesticides used in the orchards.

The effect of host weed phenology, abundance, and diversity and natural enemies on the population dynamics of the southern green stink bug, Nezara viridula (L.), in Hawaiian macadamia orchards was investigated. We found that the highest kernel damage occurred immediately following abrupt reductions in the flowering and fruiting stages of host weeds. Areas with the greatest diversity of host weeds showed higher damage, presumably because of higher N. viridula population levels. Predation rates on sentinel egg masses were highest over the two seasons in areas where the bigheaded ant, Pheidole megacephala (F.), comprised a large portion of the ant fauna. In one of the orchards, P. megacephala and the longlegged ant, Anoplolepis longipes (Jerdon), occurred in a spatial mosaic where the boundaries shifted back and forth over time. Sentinel egg masses placed in these two adjacent areas showed predation rates were highest in the areas dominated by P. megacephala, and intermediate in the interface zone and lowest where only A. longipes were found. The importance of weed phenology and natural enemy induced mortality is discussed.

As a basis for the development of both eradication and management strategies for control of Anoplophora glabripennis Motschulsky (Asian longhorned beetle) investigations of A. glabripennis dispersal were undertaken in Gansu Province, China, in 1999. Data analysis of the first year study of population dispersal, in which >16,000 adult A. glabripennis were marked and released (mass-mark recapture method), has shown that the mean dispersal distance for A. glabripennis was ≈266 m, whereas the 98% A. glabripennis recapture radius was 560 m. More notably, A. glabripennis dispersal potential over a single season was found to be 1,029 m and 1,442 m, for male and gravid female beetles, respectively, which is well over the previously reported distances. There was also a directional bias in dispersal. These results indicate that surveys for adult beetles and infested trees at a minimum of 1,500 m from previously infested trees would assist in preventing continued colonization in the current U.S. infestations in New York and Chicago, and therefore enhance efforts to eradicate A. glabripennis from the United States. Data from the second year of this study (2000) will be used to enhance a predictive model of invasion by A. glabripennis in landscapes at risk in the United States.

Probing behavior of Diuraphis noxia (Mordvilko), Russian wheat aphid, and Rhopalosiphum maidis (Fitch), corn leaf aphid, was measured on barley lines resistant and susceptible to D. noxia grown under low and high soil moisture. R. maidis reproduces similarly on both barley lines. Probing behavior was interpreted from waveforms of an alternating current electrical penetration graph (AC EPG) system of the Oklahoma design during 6-h monitoring periods. Significant effects were observed, particularly the aphid species by barley line interaction. Averaging across moisture levels, D. noxia took longer to first enter sieve element phase when probing D. noxia-resistant ‘STARS-9301B’ (306 ± 19.9 min [mean ± SEM]) than when probing susceptible ‘Morex’ (180 ± 21.6 min). In contrast, R. maidis relatively quickly entered sieve element phase on the two barley lines (average of 132 ± 13.7 min), with no detectable difference between lines. When measuring the total duration of sieve element phases, the stylets of D. noxia were in contact with phloem sieve elements of STARS-9301B for a shorter period (27 ± 10 min) than with sieve elements of Morex (111 ± 21 min). In contrast, stylets of R. maidis were in contact with sieve elements of the two barley lines for similar time periods (average of 176 ± 15.8 min). Any mediating effect of soil moisture was slight, if at all measurable, using the AC EPG system, making any interpretation of probing behavior relative to previous observations of aphid population growth affected by plant water stress untenable. In contrast, monitoring probing behavior was beneficial in assessing how plant resistance may affect aphid species differently. The differences in probing behaviors between the two aphids fed barley resistant and susceptible to D. noxia corresponded well with previous observations that D. noxia population growth was lower on D. noxia-resistant barley than on susceptible barley, while R. maidis population growth was similar on the two barley lines.

Factors influencing the development of the alatoid form of the brown citrus aphid, Toxoptera citricida (Kirkaldy), were investigated in the laboratory using Carrizo citrange as a host plant. No evidence of maternal influences on wing development was observed and nymphs were not irreversibly committed to wing development until the late second or early third instar. Both alatae and apterae were significantly larger when they developed on young, flushing terminals citrus than on older, hardening terminals. Similar numbers of late second/early third instars from high-density colonies developed wings when transferred to young and old citrus terminals, but mortality was significantly higher among aphids on the older shoots. When all adults were harvested daily from high-density colonies the percentage of aphids maturing into alatae reached a peak after about 4 d and then declined with aphid density, despite the advancing age of the plant tissues. The density of aphids in a colony was positively correlated with the proportion maturing into alatae.

Flight traps at Gainesville, in north-central Florida, operating from 1984 to spring 2000, separated butterflies migrating into the Florida peninsula (SSE ± 90°) from those migrating out of the Florida peninsula (NNW ± 90°). Five species flew southward in the fall and northward in the spring: Phoebis sennae (L.), Agraulis vanillae (L.), Junonia coenia (Hübner), Urbanus proteus (L.), and Eurema lisa (Boisduval & LeConte). Five species had significant northward flights in spring but no significant migration in fall: Pieris rapae (L.), Vanessa virginiensis (Drury), Vanessa atalanta (L.), Eurytides marcellus (Cramer), and Libytheana bachmanii (Kirtland). Danaus plexippus (L.) had a southward flight in fall but no significant migration in spring. Eurema daira (Godart) switched from a net movement northward in early fall to a net movement southward in late fall, whereas Eurema nicippe (Cramer) maintained a net movement northward throughout the fall. The major migrants differed significantly in the seasonal timing and duration of peak migration. When the numbers trapped were greatest, the proportion of those flying in the migratory direction was greatest. The numbers of spring migrants of A. vanillae increased during the course of the study, whereas both the spring and fall migrations of J. coenia declined. The fall migrations of P. sennae and U. proteus declined sharply. In 1990–1999, the fall migrations of P. sennae and U. proteus averaged only 37 and 15% of what they had averaged in 1984–1989. Reduced planting of soybeans in source areas for migrants probably contributed to these steep declines.

Many populations of organisms deplete their resources, causing population growth rates to decline as population density increases. I used the sawtoothed grain beetle, Oryzaephilus surinamensis (L.), as a model to gain insight into the mechanisms of population regulation. Eight experiments differentiated the effects of crowding and food depletion on dispersal, mortality, and reproduction. Generally, food depletion caused increased mortality of immature beetles, sharply reduced oviposition, and increased adult dispersal. Rates of birth and death were both negative exponential functions of increasing density. The experiments quantify the trade-off between food and area in population regulation. These trade-offs varied with initial abundance of larvae and adults and show the risk of ignoring abundances of any life stages when characterizing vital rates. I contrast population regulation of O. surinamensis with Tribolium sp., and suggest O. surinamensis is a good alternative for experiments on population dynamics because of better mobility and shorter development time.

A distributed-delay simulation model was developed for Frankliniella occidentalis (Pergande) on greenhouse cucumber. The life history parameters used for construction of the model were obtained from published data. The model was validated using population growth data that were obtained by sampling two greenhouse cucumber crops. Predicted population dynamics by the model were in agreement with observed greenhouse population dynamics of F. occidentalis when population densities were <550 adults and larvae per plant. Sensitivity analyses revealed that sex ratio and fecundity by females were the most sensitive parameters in the population model. The simulation model was used to determine the economic thresholds for F. occidentalis based upon previously established economic injury levels. This was done by investigating the population dynamics of F. occidentalis in situations where a pesticide was applied when the population levels exceeded the determined economic thresholds at temperatures of 20 and 25°C. The effects of initial thrips density combined with different thrips invasion rates or temperatures on the population growth of F. occidentalis were also evaluated by the simulation model.

The developmental rate and survival of immature stages of mold mite, Tyrophagus putrescentiae (Schrank), were examined at seven constant temperatures, ranging from 10 to 34°C, and a relative humidity of 90 ± 5%. The larval stage was particularly susceptible to low and high temperatures with 93.6 and 54% mortality at 10 and 34°C, respectively. The optimal temperature for development and survival appeared to be 30°C. Three nonlinear (Logan type III, Lactin, and Briere) models provided a reliable fit of the relationship between developmental rates and temperature (R_a² > 0.93) for all immature stages. The upper threshold predicted by the three models were similar for all developmental stages, ranging from 35.5°C (larvae) to 37.4°C (eggs). In contrast, the lower threshold was greater using the Briere (8.8–10.5°C) model compared with the Logan type III and Lactin model for all stages. Both Lactin and Logan III predicted similar lower threshold, though it was lower for Logan III (4.4–7.3°C) for all stages, except for the larvae, where both models predicted the same temperature threshold (6.1°C). The low thermal variations of the environments where T. putrescentiae live have probably favored similar thermal threshold variations in the different immature stages. The potential of these models to predict the development of this mite is discussed.

A field study was conducted in Alberta to examine the dynamics of diapause recruitment and survival among overwintering horn flies, Hematobia irritans (L.). Cohorts of eggs were reared in experimental manure pats created at weekly intervals from July into September in three successive years. Nondiapausing adults emerged 16–47 d after pats were created in July and August, but few emerged when pat temperatures fell below 15°C. Survival to fall emergence varied with date, but was only weakly related to pat temperature. The proportion of pupae in diapause reached 1.0 in August each year. Overwintering survival of diapausing pupae varied from 0 to 85% among dates and years, and showed a curvilinear relationship with temperature during the fly’s diapause sensitive period. Thus, flies that emerged in a given spring arose from oviposition during a 3- to 6-wk interval in the preceding fall.

Adult emergence of the gall maker Aiolomorphus rhopaloides Walker and its inquiline, Diomorus aiolomorphi Kamijo, was examined in three stands of the bamboo, Phyllostachys heterocycla Matsumura. A. rhopaloides emerged from the galls from mid-April to early May, coinciding with the bamboo bud elongation period. This synchronization suggests that eggs laid in the new shoots have a nutritional advantage for resulting larvae, and that a slight advance or delay in emergence may reduce suitable oviposition sites, causing population fluctuations. D. aiolomorphi emerged from late April to early June during the bamboo shoot elongation period and females could lay eggs in elongated shoots providing relatively higher nutrition for larvae. The difference in the gall density on P. heterocycla and P. bambusoides Siebold and Zuccarini is explained on the basis of synchronization with host plant phenology.

We tested 13 species of phytoseiid mites for prey preferences between eggs and larvae of twospotted spider mite, Tetranychus urticae Koch. In general, oligophagous, specialized spider mite predators preferred eggs whereas more polyphagous, generalist predators showed no prey-stage preference or preferred larvae: Phytoseiulus macropilis (Banks), P. persimilis Athias-Henriot, Neoseiulus longispinosus (Evans), and Neoseiulus fallacis (Garman) preferred eggs; Kampimodromus aberrans (Oudemans), Galendromus occidentalis (Nesbitt), N. barkeri Hughes, N. californicus (McGregor), N. cucumeris (Oudemans), and Typhlodromus pyri Scheuten showed no prey-stage preference; and Amblyseius andersoni Chant, Euseius finlandicus (Oudemans) and E. hibisci (Chant) preferred larvae. When the ratio of spider mite eggs to larvae was altered, adult females of E. finlandicus, G. occidentalis, N. fallacis, and P. persimilis maintained relatively constant feeding ratios, resulting in slight negative prey-stage switching due mostly to the changes in prey-stage ratios offered. However, when offered a prey-stage ratio that was biased toward eggs, adult females of T. pyri exhibited positive switching, feeding disproportionately more on eggs than would be expected given the change in the ratio offered. There was no clear trend in the effect of starvation time on prey-stage preference for N. fallacis adult females. The egg preference of N. fallacis was also not affected when individuals were reared solely on eggs or larvae of T. urticae and subsequently tested as adult females. Individuals of field-collected strains of N. fallacis and P. persimilis showed no differences in prey-stage preferences when compared with individuals from long-term reared laboratory strains of the same species. However, individuals of one field-collected strain of G. occidentalis showed a stronger preference for eggs than individuals from three other strains (one laboratory and two field-collected) of the same species.

Predator-prey systems having a specialist predator often are over-exploitive, unstable and transient while similar systems having a generalist predator show less fluctuation, more stability and regulation of prey at lower densities. These population dynamics also affect dispersal patterns between specialist and generalist predators. In this study, ambulatory and aerial dispersal were assessed for five predaceous phytoseiid mites having different degrees of predation specialization: Phytoseiulus persimilis Athias-Henriot, Specialist I; Neoseiulus fallacis (Garman) Specialist II; N. californicus Chant, Specialist II/Generalist III; Kampimodromus aberrans (Oudemans), Generalist III; and Euseius finlandicus (Oudemans), Generalist IV. In general, specialist species had more walking activity and aerial dispersal than generalist species. Somewhat different dispersal strategies were seen between N. fallacis and N. californicus. Dispersal from a prey (twospotted spider mite, Tetranychus urticae Koch) patch was earlier for the more generalized N. californicus, and N. fallacis (more specialized phytoseiid) remained without dispersing until almost all prey were eliminated. Both dispersed aerially at similar rates. In general, cues from spider mite infestations decreased dispersal of specialist phytoseiids, but either acted to increase or not affect dispersal of generalist feeding phytoseiid species.

Elevated atmospheric concentrations of CO₂ and O₃ are known to alter the chemical composition of foliage, which in turn may affect the performance of herbivorous insects. We investigated the independent and interactive effects of CO₂ and O₃ on foliar quality of paper birch (Betula papyrifera Marshall) and the consequences of chemical changes for performance of the whitemarked tussock moth Orgyia leucostigma (J. E. Smith). The experimental design was a 2 by 2 factorial, with ambient and elevated levels of CO₂ and O₃, respectively. Foliage was analyzed for concentrations of nitrogen, starch, and condensed tannins. CO₂ and O₃ independently and interactively affected nitrogen concentrations, with the elevated CO₂ O₃ treatment reducing nitrogen concentrations more than either treatment alone. Elevated CO₂ and O₃ had no significant effect on starch and tannin concentrations when administered alone but increased starch concentrations by 17% over ambient when administered together. Larvae were reared on experimental trees from egg hatch through pupation to determine treatment effects on development time and pupal mass. Larval performance measures were not statistically different among fumigation treatments, although females tended to have reduced pupal mass under the elevated CO₂ O₃ treatment. These results demonstrate that chemical responses of some plant species to elevated levels of CO₂ (560 μl L⁻¹) and O₃ (1.5 × ambient) may be of insufficient magnitude to significantly alter standard measures of individual insect performance.

The development, reproduction and longevity of corn aphids Rhopalosiphum padi (L.), Sitobion avenae (Fabricius) and Metopolophium dirhodum (Walker) were studied at 18, 22, 25, 27.5 and 30°C. Only nymphs of R. padi survived at 30°C, but the adult reproductive capacity was very low. Rhopalosiphum padi performed better than M. dirhodum at all temperatures tested, and better than S.avenae over the range of 22–27.5°C. The better performance of R. padi was due to a lower nymphal mortality, lower developmental and prereproductive times and a higher intrinsic rate of increase (r_m). Sitobion avenae had a higher r_m than M. dirhodum at all temperatures. The most suitable temperature for population development was ≈28.5°C for R. padi, 26.5°C for S. avenae and 24.5°C for M. dirhodum, suggesting the ability of aphid populations to adapt to high temperatures in the Iberian peninsula. The role of temperature as a key factor in determining aphid population dynamics in the northeastern Iberian peninsula is discussed.

Based on pheromone trap catches, a model of weekly Prostephanus truncatus (Horn) flight activity was generated for southern Benin. Using response surface regression, the following environmental variables were examined: number of rainy days per week, precipitation, minimum and maximum temperatures, minimum relative air humidity, and daylength. A time-variable, year, was included to account for the variance between years. From step-wise exclusion of variables with the lowest contribution to the model fit, a model was generated which included three environmental variables (daylength, minimum relative air humidity, and minimum temperature) that explained 55% of the total variance, and the yearly variable explaining 8%. The response surface regression analysis of P. truncatus flight activity revealed the following: (1) it was positively correlated with daylength when daily minimum temperature and relative air humidity were low, (2) it was positively associated with minimum relative air humidity when lower than 75%, (3) it was negatively associated with minimum temperature, (4) unexplained yearly variation was important for the predictive strength of the model, (5) interactions of environmental variables contributed substantially to the model fit, and (6) precipitation, both as mm rain and as number of rainy days, had little influence on P. truncatus flight activity. Independent data showed that the model predicted P. truncatus flight activity well elsewhere in southern Benin, whereas in central Benin new coefficients for the same environmental variables were needed to produce an adequate prediction. The model did not fit pheromone baited trap catches from northern Benin.

Heteroblasty describes plants whose juvenile and adult vegetative shoots differ morphologically. In Eucalyptus, heteroblasty is a common source of within-plant variation and an expression of ontogenetic aging that affects the within-tree distribution of psyllids. Using Eucalyptus globulus Labillardiere as a model system, we studied the reproductive behavior of adults of two Australian psyllid species (Ctenarytaina eucalypti Maskell and C. spatulata Taylor) on the glaucous, simple-shaped juvenile leaves and the glossy, sickle-shaped adult leaves under field conditions. We compared the ovipositional preferences and mating site preferences of the psyllids in caged pairs of juvenile and adult shoots, as well as the behavior of the psyllids after they landed on both types of shoots. Ctenarytaina eucalypti oviposited only on juvenile shoots and C. spatulata oviposited only on adult shoots. Ctenarytaina eucalypti mated primarily (88% of the time) on juvenile shoots, and C. spatulata mated only on adult shoots. After landing on both shoot types, C. eucalypti remained longer than C. spatulata on juvenile shoots, but C. spatulata remained longer than C. eucalypti on adult shoots. This is the first experimental evidence that heteroblasty in Eucalyptus affects insect reproductive behavior. These results are discussed in relation to subsequent studies on psyllid performance in this system that found that the epicuticular wax (present only on the juvenile leaves) plays a primary role in the preferences of these psyllid species for the juvenile versus adult shoots.

Flight characteristics and dispersal patterns of male fall webworms, Hyphantria cunea (Drury), were investigated in three experiments: a flight-mill experiment to estimate potential flight metrics, a wind-tunnel experiment for daily patterns of male activity, and field trials of mark-recapture for estimating dispersal patterns of males in the field. In the flight-mill experiment, males had the potential to fly over 7 km after 12 h on average and, at maximum, longer than 23 km. However, the wind-tunnel experiment revealed that a sharp peak of male response was limited to 1 h around the light-on time both in response to a synthetic sex pheromone lure and to virgin females. Thus, the actual flight period of males is limited in the field. In the mark-recapture experiment, the mean distance between recapture points and the release point on the first day was <200 m in both summer and autumn. The largest number of males was captured in the first concentric on the first and the second day despite a few males that were captured outside the first concentric. Male density seemed to be diluted uniformly and distributed outside the first concentric after the fourth day. Thus, H. cunea males did not disperse over long distances, rather the dispersal range is likely to be limited to only several hundred meters (<300 m) a day because of a limited period (30 min–1 h/day) of male mating activity in nature.

European parasitoids considered for introduction to control the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), in North America have no previous association with the target pest. In Europe, they attack primarily Lygus rugulipennis Poppius and L. pratensis (L.). Compatibility of these parasitoids and their hosts in a “new-association,” the specificity of such biocontrol agents, and the potential competition with native parasitoids are important considerations for use of European species in biological control programs against L. lineolaris. In-host compatibility and competitiveness of the exotic multivoltine parasitoids Peristenus stygicus Loan and P. digoneutis Loan with the native parasitoids Leiophron lygivorus (Loan) (multivoltine), P. pallipes (Curtis) and P. pseudopallipes (Loan) (both univoltine) were assessed. Dissection of hosts indicated that >92% of the parasitoid attacks on L. lineolaris nymphs resulted in oviposition and development of the larvae for the five species studied. In suitability tests, 84% of P. stygicus adult wasps emerged from parasitized tarnished plant bugs, compared with 67 and 69% for P. digoneutis and L. lygivorus, respectively. No emergence was recorded for P. pallipes, and only 2.9% of adult P. pseudopallipes emerged. P. digoneutis was superior in the in-host competition with P. stygicus and L. lygivorus. Peristenus stygicus was dominant in the in-host competition with the three North American parasitoids. The size of the dominant larva inside the host for P. stygicus 7 d after oviposition decreased as the number of larvae increased.

Two experiments were carried out in the laboratory to evaluate the effect of a formulation of the nuclear polyhedrosis virus (NPV) of the velvetbean caterpillar, Anticarsia gemmatalis Hübner (AgNPV), on the predator Podisus nigrispinus Dallas. In the first experiment, predators were exclusively fed A. gemmatalis reared on artificial diet, treated with one formulation of the AgNPV (infected prey) or with water (healthy prey) as the control. In the second experiment, an additional treatment was incorporated in which the artificial diet was treated with an inactive (autoclaved) AgNPV formulation. The predators were fed on these exclusive prey during their entire lifespans for three or four consecutive generations, during the first and second experiment, respectively. Daily observation of oviposition and mortality were performed to provide data for the construction of fertility life tables and to determine daily oviposition patterns and survival distribution curves. For both experiments, no adverse effects were observed in the first generation. However, significant effects in the predator population were observed throughout the subsequent generations, when the predators were fed with prey that fed on infective or inactivated AgNPV diet compared with the healthy prey. The adverse effects observed might be due to some inert components present in the commercial formulation, because the AgNPV has been demonstrated to be highly specific to Lepidoptera and neither does it replicate nor has any adverse effect on P. nigrispinus. The fertility life tables proved to be a good tool to measure the potential impact of biopesticides on nontarget population under laboratory conditions.

RESUMO Dois experimentos foram realizados em condições de laboratório para avaliar o efeito de uma formulação comercial de Vírus da Poliedrose Nuclear da lagarta da soja, Anticarsia gemmatalis Hübner (AgNPV) na biologia de Podisus nigrispinus Dallas. No primeiro experimento, os predadores foram alimentados exclusivamente com A. gemmatalis criadas em dieta artificial, tratada com uma formulação de AgNPV (presa infectada) ou com água (presa sadia), como controle. No segundo experimento, foi incorporado um tratamento adicional no qual a dieta artificial foi tratada com uma formulação de AgNPV inativada (autoclavada). Os predadores foram alimentados com essas presas exclusivas durante toda a vida por três ou quatro gerações consecutivas, durante o primeiro e o segundo experimentos, respectivamente. Observações diárias da oviposição e mortalidade foram feitas para se obter dados para a construção de tabelas de vida de fertilidade e para determinar os padrões de oviposição diária e distribuição das curvas de sobrevivência. Para ambos os experimentos, não foram observados efeitos adversos na primeira geração. Contudo, efeitos significativos sobre a população do predador foram observados nas gerações subsequentes nos tratamentos com AgNPV ativo e inativado, mas não com o controle. Os efeitos adversos observados poderiam ser atribuidos a componentes inertes presentes na formulação comercial do biopesticida, uma vez que o AgNPV tem demonstrado ser altamente seguro a organismos não alvos e especifico para lepidopteros. As tabelas de vida mostraram ser uma boa ferramenta para se medir efeitos de biopesticidas sobre diversos parâmetros biológicos de populações de organismos não alvo.

Parasitoid-pathogen interactions were examined using gypsy moth, Lymantria dispar (L.), Bacillus thuringiensis Berliner, and Compsilura concinnata (Meigen). The objectives of this study were to quantify effects of sublethal doses of Bacillus thuringiensis (Bt) force-fed to gypsy moths and to determine if sublethal doses of Bt affected host acceptance and suitability of gypsy moth for C. concinnata. Gypsy moths were minimally affected by sublethal doses of Bt; development of fourth instar was delayed, and male pupal mass reduced. Compsilura concinnata preferentially attacked and had higher superparasitism on noninfected hosts than on Bt-treated larvae. Exposure of gypsy moth to both sublethal doses of Bt and parasitoids reduced percentage parasitism and host larval survivorship. Effects on C. concinnata development varied with host superparasitism status. Parasitoids in Bt-treated, superparasitized gypsy moths had shorter larval development times and smaller pupal masses than parasitoids in untreated larvae, while parasitoids in singly parasitized larvae had larger pupal masses than those in superparasitized larvae. Timing of Bt infection relative to parasitism is a factor in gypsy moth mortality, but not in parasitoid potential fecundity.

Effects of prey density and adult predator size on food consumption and oviposition were evaluated in an aphidophagous ladybird beetle, Menochilus sexmaculatus (F.), from tropical Asia. Both the functional response and reproductive numerical response showed an upper asymptote at 40 adult Aphis craccivora Koch/female/150 cm². Proportions of aphids consumed and eggs laid by female beetles were highest at lower aphid densities, i.e., five or 10 adult aphids. Ratio of eggs laid to aphids consumed, by dry weight, was highest at the lowest aphid density, i.e., five adult aphids. Larval food supply significantly influenced the size of adult females. After 24 h, smaller females consumed significantly fewer aphids and laid fewer eggs in comparison to larger females, but conversion efficiency from food to eggs remained the same irrespective of the difference in adult size. Results suggested that this ladybird species exploit prey efficiently at low density.

It has been shown that honey bees (Apis mellifera L.) adsorb bacterial spores as a function of the electrostatic charge on the bee and concentration of bacteria in the aerosol during tethered flight in wind tunnel experiments. This report presents a mathematical model for predicting the number of spores that could be adsorbed onto free-flying bees passing through a bacterial spore aerosol plume/cloud and experimental validation of this model. The model accounts for the geometry of the aerosol dispersion from a continuous point source, aerosol particle settling, and adsorption and desorption rates onto/off of bees based on laboratory observations of tethered flying honey bees.